Big operators for finsupps #
This file contains theorems relevant to big operators in finitely supported functions.
Declarations about sum
and prod
#
In most of this section, the domain β
is assumed to be an AddMonoid
.
sum f g
is the sum of g a (f a)
over the support of f
.
Equations
- Finsupp.sum f g = Finset.sum f.support fun a => g a (↑f a)
Instances For
prod f g
is the product of g a (f a)
over the support of f
.
Equations
- Finsupp.prod f g = Finset.prod f.support fun a => g a (↑f a)
Instances For
A restatement of sum_ite_eq
with the equality test reversed.
A restatement of prod_ite_eq
with the equality test reversed.
If g
maps a second argument of 0 to 0, summing it over the
result of onFinset
is the same as summing it over the original Finset
.
If g
maps a second argument of 0 to 1, then multiplying it over the
result of onFinset
is the same as multiplying it over the original Finset
.
Taking a sum over over f : α →₀ M
is the same as adding the value on a
single element y ∈ f.support
to the sum over erase y f
.
Taking a product over f : α →₀ M
is the same as multiplying the value on a single element
y ∈ f.support
by the product over erase y f
.
Generalization of Finsupp.add_sum_erase
: if g
maps a second argument of 0
to 0, then its sum over f : α →₀ M
is the same as adding the value on any element
y : α
to the sum over erase y f
.
Generalization of Finsupp.mul_prod_erase
: if g
maps a second argument of 0 to 1,
then its product over f : α →₀ M
is the same as multiplying the value on any element
y : α
by the product over erase y f
.
Deprecated, use _root_.map_finsupp_sum
instead.
Deprecated, use _root_.map_finsupp_prod
instead.
Deprecated, use _root_.map_finsupp_sum
instead.
Deprecated, use _root_.map_finsupp_prod
instead.
Deprecated, use _root_.map_finsupp_sum
instead.
Deprecated, use _root_.map_finsupp_prod
instead.
Taking the product under h
is an additive homomorphism of finsupps, if h
is an
additive homomorphism on the support. This is a more general version of
Finsupp.sum_add_index'
; the latter has simpler hypotheses.
Taking the product under h
is an additive-to-multiplicative homomorphism of finsupps,
if h
is an additive-to-multiplicative homomorphism on the support.
This is a more general version of Finsupp.prod_add_index'
; the latter has simpler hypotheses.
Taking the sum under h
is an additive homomorphism of finsupps,if h
is an additive
homomorphism. This is a more specific version of finsupp.sum_add_index
with simpler
hypotheses.
Taking the product under h
is an additive-to-multiplicative homomorphism of finsupps,
if h
is an additive-to-multiplicative homomorphism.
This is a more specialized version of Finsupp.prod_add_index
with simpler hypotheses.
The canonical isomorphism between families of additive monoid homomorphisms α → (M →+ N)
and monoid homomorphisms (α →₀ M) →+ N
.
Equations
- One or more equations did not get rendered due to their size.
Instances For
For disjoint f1
and f2
, and function g
, the sum of the sums of g
over f1
and f2
equals the sum of g
over f1 + f2
For disjoint f1
and f2
, and function g
, the product of the products of g
over f1
and f2
equals the product of g
over f1 + f2
If 0 : ℕ
is not in the support of f : ℕ →₀ ℕ
then 0 < ∏ x in f.support, x ^ (f x)
.